Machining unit for a program-controlled milling and drilling machine

ABSTRACT

A machining unit for a program-controlled milling and drilling machine. A head support movable in several coordinate axes has an axis of rotation pointing forward and downward at a 45° angle. A swivel head arranged on a front side of the head support is rotatable about the axis of rotation. A spindle nose is fixedly mounted on the swivel head and has a working spindle with an axis extending at an angle of 45° relative to the axis of rotation. A spindle motor is aligned coaxially with the axis of rotation and a bevel gear arranged in the swivel head for the motor shaft. The swivel head has a cylindrical hollow housing member coaxial with the axis of rotation and in which the spindle motor is mounted. The head support has a housing neck in which the housing member of the swivel head is rotatably supported.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to machine tools, andmore specifically to a machining unit for a program-controlled millingand drilling machine.

[0003] 2. Discussion of Related Art

[0004] Machining units having swivel and/or rotary heads for selectivelymachining a workpiece horizontally or vertically at one position, havebeen used for some time. Such units typically carry a working spindleand provide movement of the spindle in horizontal and vertical axes.

[0005] German patent publication 44 02 084 describes a machining unithaving a support housing movable along a machine column. In this unit,the end wall is slanting with respect to vertical by 45° and isdownwardly inclined. The end wall guides a swivel milling head having amounting surface also inclined by 45° relative to the vertical. Theswivel milling head carries a working spindle arranged at 45° relativeto the axis of rotation which, by corresponding rotation of the swivelmilling head, can be pivoted between horizontal and vertical machiningpositions. The support housing for the swivel head accommodates acontrollable motor having a shaft coaxial with the axis of rotation. Theshaft drives the working spindle via a pair of bevel gears and a set ofsliding gears at two different speeds, as desired.

[0006] One shaft of the spindle motor is hollow and surrounds a solidshaft passing through the motor housing and the swivel head with enoughclearance for turning the swivel head. A worm drive is attached to theinner end of the hollow shaft. The housing of the swivel head is mountedon the outer lower end of the shaft. An annular swivel head endprojection, coaxial with the 45° axis of rotation, includes radialserrations. An annular recess of the head support accommodatescomplementary radial serrations. The swivel head is positively fixed ata specified angular position by positive engagement of both radialserrations. The central solid shaft is axially slidable and connectedwith a resiliently biased pressure medium cylinder via an end plate.

[0007] In this known device, the fixation of the swivel head at givenangular positions means that machining of a workpiece is only possibleat given spindle positions. In addition, the manner of fixing the swivelhead is relatively complicated.

SUMMARY OF THE INVENTION

[0008] The present invention relates to a machining unit for aprogram-controlled milling and drilling machine. In one embodiment ithas a head support movable in several coordinate axes and includes anaxis of rotation pointing forward and downward by 45°. A swivel head isarranged at a front face of the head support and is rotatable about theaxis of rotation. A spindle nose is fixedly mounted on the swivel headand has a working spindle with an axis extending at an angle of 45°relative to the axis of rotation.

[0009] It is one object of the invention to provide a machining unit fora milling and drilling machine, with a simplified structural design andincreased rigidity. It is also an object to enable more universaloperations, for example, machining a workpiece while the milling head ispivoted.

[0010] In one embodiment of the present invention, the swivel head has acylindrical hollow housing member coaxial with the axis of rotation. Thespindle motor is fixed, in the housing member, and the head support hasa cylindrical hollow housing neck in which the housing member of theswivel head is rotatably supported.

[0011] Fixation of the entire spindle motor in the swivel head and therotatable support of the cylindrical hollow housing member, fixedlyconnected with the motor housing of the swivel head in the head support,ensures that when the swivel head is rotated about the 45° axis ofrotation, the spindle motor also rotates together with the train ofgears and the working spindle. This is accomplished without causingrelative motions of the individual elements of this entire assembly.Fixation of the swivel head at a given angular position by positiveengagement of radial serrations is not made so that the machining unitenables operations at any angular positions and also during a rotarymotion of the swivel head. The disclosed arrangement of the spindlemotor and support of the swivel head in the head support enables the useof powerful spindle motors and also increased cutting capacities whilethe dimensions of the machining unit remain approximately the same.

[0012] A direct electric drive coaxial relative to the 45° axis ofrotation, or a conventional electric motor, can be used as a rotarydrive for the swivel head. The motor is kinematically connected with atoothed ring mounted motor housing via a toothed belt drive. Clearanceis provided with clamping and a spur gear. Such a drive train ensures aclearance-free transmission of high torques and the highly accuratepositioning of the swivel head at given angular positions.

[0013] The swivel head is suitably supported within the housing of thehead support by means of a supporting ring attached to the cylindricalhollow housing neck and engaging a peripheral groove. This peripheralgroove is formed in the cylindrical hollow housing member of the swivelhead. The ring is supported in the groove by means of three rollingbearings.

[0014] In prior swivel heads, the supply of energy, control signals, andrinsing liquid to the working spindle creates difficulty due to theconfined space. In the present inventions this is addressed by theprovision of an external flexible pipe for the protecting electric andliquid lines. This pipe extends from the head support to the housing ofthe working spindle, preferably in an arcuate fashion. The flexible pipeis connected with the head support by a turnable elbow connector. Thepipe is pivotably connected with the spindle housing via an adapter.

[0015] The adapter design provides the desired pivoting capacity of thepipe connection with the spindle housing. For example, a bushing isprovided having a convex external surface against which a pivotable endring bears in a sliding fit. In order to prevent the electric and liquidlines from being damaged, the adapter may have freely rotatable rollingelements, in particular, rollers, against which the different linesabut.

BRIEF DESCRIPTION OF THE DRAWING

[0016] Further particularities and advantages of the invention willbecome clear from the following description of preferred embodimentswith reference to the drawing, in which:

[0017]FIG. 1 is a perspective view of a machining unit according to oneembodiment of the invention;

[0018]FIG. 2 shows a sectional view of the machining unit according tothe FIG. 1 embodiment;

[0019]FIG. 3 is a perspective exploded view of the flexible pipe usedfor the machining unit according to FIG. 1 and having connections onboth sides; and

[0020]FIG. 4 shows a sectional view of the pivotable end connection ofthe flexible pipe with the adapter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] According to FIG. 1, the machining unit has angular head support1, which comprises vertical rear plate-like or frame-like supportstructure 2, bulky central portion 3 and cylindrical hollow housing neck4. The head support is inclined forwardly and downwardly at an angle of45°. Swivel head 5 is rotatably supported in the head support about axisof rotation 27 of cylindrical hollow housing neck 4. On one side of theswivel head spindle nose 6 is rigidly mounted at a 45° angle withrespect to axis of rotation 27 of housing neck 4. Working spindle 7 issupported transversely in the spindle nose. Flexible pipe 9 is pivotablyconnected to box-like rear portion 8 of the spindle nose by means ofadapter 10. The top end of the flexible pipe communicates with the bulkycentral portion of the head support via rotatable elbow connector 11.

[0022]FIG. 2 shows a diagrammatic vertical section of the internalfunctional parts of the machining unit according to the FIG. 1embodiment. Head support 1 accommodates adjusting motor 15. Theadjusting motor has a shaft to drive toothed belt 16. The toothed beltmaintains a constant clamping. This is part of what is understood hereinas a cyclo drive. The toothed belt runs over two toothed gears 17. Thesegears are slightly displaced angularly with respect to each other (onlyone of which is shown in FIG. 2). Each toothed gear drives shaft 18 andpinion 19 mounted thereon. The pinion meshes with spur ring 20 mountedon motor housing 21. The motor housing is formed as a hollow cylinderaround spindle motor 22. Stator 23 of spindle motor 22 is fixedlyattached to motor housing 21 via sleeve 24. The sleeve is provided withcooling channels, as shown in FIG. 2. Rotor 25 of the spindle motor isfixedly attached to hollow shaft 26. As can be seen in FIG. 2, the axisof rotation 27 of hollow shaft 26 is inclined downwardly at an angle of45° relative to vertical.

[0023] Bevel gear 28 is located on the protruding end of hollow shaft26. This bevel gear meshes with bevel wheel 29. The bevel wheel is partof spur gear 32 mounted on shaft 31. The bevel wheel is freely rotatablein housing 30 of the swivel head. Spur gear 32 meshes with the majorpart of sliding gear 33 mounted on countershaft 34. Sliding gear 33meshes with radial serrations 35 along the outer periphery of workingspindle 36. Relatively large toothed gear 37, by moving sliding gear 33on countershaft 34, engages smaller spur wheel 38. Toothed gear 37 isdisposed on a front portion of working spindle 36.

[0024] Housing member 40 is coaxial with respect to axis of rotation 27and engages cylindrical hollow housing neck 4 of head support 1. Robustand dimensionally stable supporting ring 41 is mounted on the internalwall of housing neck 4. This ring is guided in a peripheral grooveformed in housing member 40 by means of three rolling bearings 42designed for supporting radial and axial loads.

[0025] In order to horizontally machine a workpiece, a tool is clampedinto working spindle 7, and spindle motor 22 attached to the housing ofswivel head 5 is switched to the ON position. As can be seen in FIG. 2,hollow motor shaft 26 drives working spindle 7 through bevel gear 28,bevel wheel 29, sliding gear 33, and radial serrations 35. In order toplace spindle nose 6 in an inclined or vertical position, adjustingmotor 15 is switched on. Motor housing 21 turns about axis of rotation27 through toothed belt 16, toothed gear 17, pinion 19, and spur ring20. Since motor housing 21 is fixed with cylindrical hollow housingmember 40 of swivel head 5, the rotation motion of spindle motor 22effects a corresponding rotary or swivel motion of swivel head 5 andalso of spindle nose 6 about axis of rotation 27. These rotary or swivelmotions of swivel head 5 and spindle nose 6 are independent of the driveof working spindle 7.

[0026] Flexible pipe 9, as shown in FIGS. 1, 3, and 4, preferably has arelatively high compressive strength and a sufficient flexibility forthe application. In FIG. 3, elbow connector 11 is mounted on the top endof flexible pipe 9 by means of a conventional pipe clip. Rotary ring 50,spring ring 51, and end ring 52 are mounted on the outlet side of elbowconnector 11 such that the elbow connector can be rotated about thecentral axis of rings 50, 51, and 52.

[0027] Referring now to FIG. 4, adapter 53, shown in longitudinalcross-section, is mounted on the other end of flexible pipe 9 by meansof a conventional pipe clip. This adapter contains ring body 54approximately rectangular in cross-section, to which an also rectangularinsert 55 is attached by means of screws. Upper and lower surfaces 56and 57 of the insert are convex or have an arc shape. Top portion 58 andbottom portion 59 of rectangular end member 60 are guided in a slidingfit on convex surfaces 56 and 57. Two lateral rolls 61 and 62 aresupported in end member 60 as shown. As can be seen in FIG. 1, endmember 60 is attached to box-like rear portion 8 of spindle nose 6. Thelength of flexible pipe 9 and the positions of both connections 10 and11 are chosen such that the flexible pipe approximately maintains itsflexibility and so that only the positions of elbow connector 11 andadapter 10 are affected when spindle nose 6 is moved about axis ofrotation 27.

[0028] The invention is not limited to the above described embodiments.For example, depending on the desired application, elements 33 to 38,which are referred to herein as “speed changing gears,” may be omitted.In this case spur gear 32 directly engages radial serrations 35 onworking spindle 36, when the diameters are enlarged correspondingly.This results in the dimensions of the machining unit being smaller.Instead of the drive shown in FIG. 2, which consists of adjusting motor15, toothed belt 16 and toothed gears 17, shaft 18, and pinion 19, it isalso possible to use a direct electric drive described as follows. Thecylindrical hollow stator is mounted in the interior of head support 1and the rotor is attached to housing member 40 and/or to housing 21 ofspindle motor 22.

[0029] An alternative support arrangement can provide stable support ofswivel head 5. This arrangement is highly loadable in the axial andradial directions and enables accurate easy rotary motions of the swivelhead about axis of rotation 27. In order to fix the swivel head atpreselected positions, also in the case of extremely high loads, anadditional clamping means can be provided between a suitable componentof the head support and the swivel head. This clamping means can beactuated hydraulically and/or mechanically and has at least onedisk-like or sleeve-like clamping element as shown, for example, inGerman patent publications 195 22 711 and 41 22 711. In addition, theflexible pipe, elbow connector, and adapter can also be used for othermachining units which have a swivel head rotatable about a 45° axis ofrotation and have a fixedly attached working spindle.

[0030] While the present invention has been illustrated and described bymeans of specific embodiments, it is to be understood that numerouschanges and modifications can be made therein without departing from thespirit and scope of the invention. Accordingly, the invention is limitedonly by the claims.

What is claimed is:
 1. A machining unit for a program-controlled milling and drilling machine, said machining unit comprising: a head support movable in several coordinate axes, said support having a front face and an axis of rotation pointing forward and downward by 45°; a swivel head arranged on the front face of the head support; a spindle nose fixedly attached to the swivel head, said spindle nose further comprising a working spindle, said spindle nose being arranged at an axis at an angle of 45° relative to said axis of rotation of said head support; a spindle motor mounted in the head support, said motor aligned coaxially with respect to said axis of rotation of said head support, and said motor having a shaft for rotating the swivel head about the axis of rotation of the head support; and a bevel gear arranged on the protruding end of the shaft, the swivel head further having a cylindrical hollow housing member coaxial with respect to the axis of rotation of the head support, and the head support having a housing neck in which the housing member of the swivel head is rotatably supported.
 2. The machining unit of claim 1, wherein the head support further comprises a rotary drive for turning the swivel head, said rotary drive having a clearance-free clamped gear train including a toothed belt drive and a pinion, said pinion constantly engaging a spur ring mounted on the motor.
 3. The machining unit of claim 1, wherein a speed changing gear arrangement is positioned downstream of the bevel gear.
 4. The machining unit of claim 2, wherein a speed changing gear arrangement is positioned downstream of the bevel gear.
 5. The machining unit according to claim 1, wherein at least one supporting ring is mounted in the cylindrical hollow housing neck of the head support, and wherein said ring is supported in at least one peripheral groove formed in the housing member of the swivel head.
 6. The machining unit according to claim 4, wherein at least one supporting ring is mounted in the cylindrical hollow housing neck of the head support, and wherein said ring is supported in at least one peripheral groove formed in the housing member of the swivel head.
 7. The machining unit according to claim 1, wherein a front half portion of the spindle motor housing is fixed by the housing member of the swivel head and a rear portion of the spindle motor housing containing the spur ring projects into the head support.
 8. The machining unit according to claim 5, wherein a front half portion of the spindle motor housing is fixed by the housing member of the swivel head and a rear portion of the spindle motor housing containing the spur ring projects into the head support.
 9. The machining unit according to claim 6, wherein a front half portion of the spindle motor housing is fixed by the housing member of the swivel head and a rear portion of the spindle motor housing containing the spur ring projects into the head support.
 10. The machining unit according to claim 1, wherein the spindle nose has a box-like rear portion and wherein an external flexible pipe adapted for protecting electrical and liquid lines extends from the head support to said box-like rear portion.
 11. The machining unit according to claim 10, wherein the flexible pipe is connected to the head support via a rotating elbow connector and is pivotably connected to the box-like portion of the spindle nose via an adapter.
 12. The machining unit according to claim 11, wherein the adapter contains a bushing having convex external surfaces against which a pivotable end ring abuts in a sliding fit.
 13. The machining unit according to claim 11, wherein rolling elements are supported in the adapter.
 14. The machining unit according to claim 12, wherein rolling elements are supported in the adapter. 